These weapons, drones, and battlefield devices—some recently deployed, others in early R&D—will help the Pentagon fight more effectively with fewer troops.

Railgun

Railgun

The concept has been around for nearly a century: use electromagnetism instead of explosive charges to fire artillery rounds. The U.S. Navy has been working on just such a weapon since 2005—a railgun prototype that's compact enough for a ship. Designed to support Marines during land strikes and harass enemy vessels from afar, the prototype harnesses a 32-megajoule jolt of electricity to launch a 23-pound shell that can destroy targets up to 110 miles away with kinetic energy alone. (One megajoule is the energy equivalent of a 1-ton vehicle moving at 100 mph.) Here's how the railgun works: High-voltage capacitor banks are connected to two copper rails—one positively charged (1) and the other negatively charged (2). To fire the weapon, a current pulses down the positively charged rail, across a conductive armature (3) that cradles a shell (4), and up the negatively charged rail. The completed circuit generates powerful electromagnetic fields that propel the armature and shell along the rails at tremendous velocity. At the end of the rails, the shell detaches (5) from the armature and speeds to its target at more than 5600 mph. The launch sequence takes 10 milliseconds. The Navy plans to start shipboard tests in 2016.

Smart-Scope Rifle

Smart-Scope Rifle

A Texas company called TrackingPoint has developed a laser-guided, semiautomatic rifle with a networked tracking scope that measures distance, humidity, and 16 other ballistic variables. The payoff is high first-shot precision on targets up to 750 yards away. Shown here on the AR 762, the scope also streams live video from its Heads Up Display to smartphones and tablets. Other fighters could use the video to acquire targets; commanders could use it to assess battlefields in real time. The Army began testing a military version of the rifle in May.